I had bloods taken last Wednesda at a hospital. On Friday evening my surgery rang and said we have had a message about your bloods, that were taken Wednesday; they appear to be concerned about my Free T4 which is
1.6pmlo/L (12.3-20.2)
I am on 4x 25mcg of T3 only
Is this ok to be out of range on T3 only ?
Thank you in advance
Yes it is, when you are on T3 only. Mine is about 2 with a reference range of 12 - 22.
However, if you are on T3 only there is really little point in testing Free T4, and every point in testing Free T3. But labs can't cope with that idea apparently...
Thank you humanbean, I know the TSH is suppressed on T3 as well, wasn't sure about the free T4, I don't know why they don't do Free T3?
I think it is to save money. Doctors have also convinced themselves that it is not a useful measurement for people who are hypothyroid. All that counts is TSH, and at a push, possibly Free T4 as well, but only if TSH is below or above range.
I guess it's because they are not taught to fully understand how T3 behave as it has so different mechanism.
Like for example in early hypothyroidism ft3 can be high normal because your body compensate the lack of T4 and conversion increase until you hit late stage = severe hypothyroidism when you do not have what to convert.
Or in ID ft3 can be above the range which falsely looks like thyrotoxicosis.
In early hashimoto ft4 can be high with low TSH and low ft3 as your body is trying to prevent you going hyper, then rt3 is high to get rid of excess T4.
And so on and so on.
They are not taught how to interpret the bigger picture, therefore someone on T3 only puzzles them so much.
Even though I know , several doctors have confirmed this, it is clearly written in the text book they go through at medical school. It's all there. They just do not have brain to read the whole book.
Over here on finland laboratory technicians know more about thyroid than doctors. I have access to most laboratory manuals and they tell how to interpret the numbers. And this is confirmed by doctors (those who understand thyroid).
Thank you, I know they don't want to do any bloods other the TSH. At a pinch I sometimes get others done.
It's sad. Maybe you could print out some information to have with you where it is explained so you could try to make them understand why ft4 in your case is low and nothing to worry about as long as you are feeling good?
You could say that you understand the surgery and the staff have their rules and guidelines which you cannot change, but you'd like to point out that the numbers are different on T3 only , and it's nothing but a fact.
100% it does. Not allow photos to be uploaded definitely 1.6 pmlo/L
Of course her FT4 can be 1.6, mine is zero, because we're both on T3 only.
I'm sure financial implications of tests also makes a difference. I guess if we didn't have the NHS, thyroid problems could be quite a financial burden for us too 
Hospital denying T4 and T3 bloods taken
Trying to balancing T3 and T4 
Starting T3 with T4 advice please 
is it best to up T3 or T4? Results in comments 
T3 and T4 flood results
